In recent years the Internet and the Internet Protocol have played a larger role in the field of telecommunications. Packet data protocols, such as the Internet Protocol (IP), have been used to deliver packet and voice services to subscribers. Voice over IP is one example of a packet data protocol being used to deliver voice services to telecommunications subscribers. Telecommunications networks, however, must be configured to support this new paradigm of providing voice services.
In the past, an area receiving telecommunications service may receive the service through a dedicated circuit or circuit group of some type. In the wired world, this dedicated circuit may take the form of a trunk or a dedicated time-slot on a trunk. Because each call is allocated a dedicated circuit, there was a high degree of predictability of bandwidth once a circuit was allocated for a communication session. There were also a predictable number of voice circuits available once a circuit group was established. Delivering Real Time Transport Protocol (RTP) packets in a VoIP network is not as predictable. Because of the unpredictable nature of packet networks, voice calls routed over packet networks tend to be less reliable. Call failures caused by this unreliability may be more common.
In the realm of VoIP calls, an area served is typically referred to as a service group or packet group. A certain number of IP addresses may be allocated to a service group. If too many calls are routed to a service group or if a service group is experiencing technical difficulties, call failures may occur in configuring an RTP session between two IP endpoints. This type of call failure may occur before a bearer is allocated at the RTP server, which may cause call failures. If too many call failures occur, calls may need to be re-routed to a different service group. Or, if call failures are frequent, the number of IP addresses allocated to a service group may have to be modified. Thus, the number failures and types of failures occurring in a service group must be monitored.